But the two heavyweights in the smartphone world -- Samsung and Apple -- have yet to jump into the arena. When they do, the direction each takes could tip the scales toward one of three industry specifications vying for supremacy in wireless charging.

An iPhone with a wireless charging case charging on a PMA-style pad (photo: Starbucks).

Mobile handset maker Kyocera Communications on on Monday trumpeted that it's "proud to be one of the first manufacturers to bring PMA-enabled smartphones to the U.S. market." The "PMA," or Power Matters Alliance, is one of the three groups vying for market dominance with its Powermat wireless charging specification -- and it's the technology Starbucks is using.

The other two wireless charging groups are the Alliance For Wireless Charging woth its Rezence spec and the Wireless Power Consortium (WPC), which touts the most popular version of them all, the Qi (pronounced "chee") standard.

Since May, Sprint and Virgin Mobile US have both been offering the Kyocera Hydro Vibe, a low-end smartphone, with PMA wireless charging built in.

Kyocera is launching its Hydro Icon with Boost Mobile on June 18; it can come enabled for both Powermat and Qi-style wireless charging.

Kyocera is exclusively a member of the PMA, but many of the other handset and internal processor makers -- as members of all three wireless power groups -- are hedging their bets. For example, Samsung and wireless charging processor maker Texas Instruments are members of all three groups.

AT&T now offers an upgrade for the Samsung Galaxy S5, which supports the PMA specification. And an add-on case for the Apple iPhone is available from Duracell Powermat.

However, of the 20 million consumer devices estimated to have shipped in 2013 with wireless charging capabilities, nearly all were built with the Qi specification, according to IHS. The bulk of that Qi technology went into devices such as the Google Nexus 4 and 5 smartphones, Google's Nexus 7 second-generation tablet and a number of models in Nokia's Lumia line-up.

Rumors have been percolating for months that Apple will offer wireless charging on the iPhone 6, which is expected out this fall. Of course, that and $1.65 will get you a Starbuck's grande coffee.

What has frequently accompanied the iPhone 6 wireless charging rumors are concerns that Apple will use its own proprietary specification rather than one of the three currently being touted by industry groups.

"Makes sense," said Mikey Campbell, an editor with AppleInsider. "They already require their own cables (Lightning, the erstwhile 30-pin). Why not make some cash with a new standard, license it out through MFi. Money!"

Ryan Sanderson, an associate research director with IHS, agreed that if Apple were to choose one standard or even come out with its own "which is also a real possibility," it would certainly have an impact.

"With the momentum that appears to be building to come out with its own standard or proprietary solution, it's likely it would have to happen in one of its next 2 major generations," Sanderson said.

On the other hand, if Apple were to pick one of the current industry specifications, it would "obviously bode in favor of that standard and could really change the playing field," Sanderson added.

While an iPhone with wireless charging would certainly spur the market, Samsung holds the greatest market share and, therefore, has the greatest influence in the coming wireless charging war, according to Sanderson.

Among the combined global shipments of mobile phones and tablets in 2013, Samsung had 28% of the market, more than double Apple's 13%. By 2018, Samsung's lead is forecast to be even bigger, with Samsung accounting for 31% of shipments, Apple, 14%, Sanderson said.

"So perhaps the bigger question should be, 'What is the impact if Samsung chooses one side or the other?'" Sanderson said.

According to IDC, now that Apple has finally arrived at China Mobile, "it remains to be seen how much Apple will close the gap against Samsung in 2014."

Huawei, which held the No. 3 position in handset shipments, attained the highest year-on-year increase among the leading vendors. Lenovo follows in the No. 4, followed by LG and ZTE.